Electronic component

ABSTRACT

An electronic component includes a laminate in which a plurality of dielectric layers and a plurality of internal electrodes are alternately laminated and external electrodes electrically connected to the internal electrodes. A side margin portion as a region in which the plurality of internal electrodes is not provided when a section of the laminate having the length direction and the width direction is viewed from the laminating direction includes a plurality of side margin layers laminated in the width direction. An outer layer portion as a region in which the plurality of internal electrodes is not provided except for the side margin portion when a section of the laminate including the laminating direction and the width direction is viewed from the length direction includes a plurality of layer-margin layers laminated in the laminating direction.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese PatentApplication No. 2018-158350 filed on Aug. 27, 2018. The entire contentsof this application are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to an electronic component.

2. Description of the Related Art

In the related art, an electronic component including a laminate inwhich a plurality of internal electrodes and a plurality of dielectriclayers are alternately laminated is known. As one of such electroniccomponents, a multilayer ceramic capacitor in which external electrodesare formed on both end surfaces of a laminate is disclosed in JapanesePatent Application Laid-Open No. 2017-178684. Here, a region in whichthe internal electrodes are not provided in a section of the laminateviewed from a laminating direction is referred to as a side marginportion. A region in which the internal electrodes are not provided onboth outsides of the internal electrodes in the laminating direction isreferred to as an outer layer portion.

Here, in manufacturing of a multilayer ceramic capacitor, although anunfired laminate is fired, a shrinkage behavior during firing isdifferent between a portion as an inner layer portion in which internalelectrodes and dielectric layers are alternately laminated and a portionas the side margin portion and the outer layer portion in which theinternal electrodes are not provided. Due to the difference in shrinkagebehavior, peeling may occur between the layers in the laminate, and agap may be formed.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide electroniccomponents in each of which an occurrence of peeling or a gap betweenlayers in a laminate is reduced or prevented.

According to a preferred embodiment of the present invention, anelectronic component includes a laminate in which a plurality ofdielectric layers and a plurality of internal electrodes are alternatelylaminated, and an external electrode electrically connected to theinternal electrodes. The laminate includes a first main surface and asecond main surface opposing each other in a laminating direction, afirst side surface and a second side surface opposing each other in awidth direction perpendicular or substantially perpendicular to thelaminating direction, and a first end surface and a second end surfaceopposing each other in a length direction perpendicular or substantiallyperpendicular to the laminating direction and the width direction. Aside margin portion is a region in which the plurality of internalelectrodes is not provided when a section of the laminate having thelength direction and the width direction is viewed from the laminatingdirection, and includes a plurality of side margin layers laminated inthe width direction. An outer layer portion is a region in which theplurality of internal electrodes is not provided, further to the sidemargin portion, when a section of the laminate having the laminatingdirection and the width direction is viewed from the length direction,and includes a plurality of layer-margin layers laminated in thelaminating direction.

A boundary may be provided between the side margin portion and the outerlayer portion in the laminating direction. Si may be included in theplurality of layer-margin layers. A content of Si included in one of thelayer-margin layers located on an outermost side in the laminatingdirection among the plurality of layer-margin layers may be larger thana content of Si included in remaining ones of the layer-margin layersother than the one of the layer-margin layers located on the outermostside.

Si may be included in the plurality of side margin layers. A content ofSi included in one of the side margin layers located on an outermostside in the width direction among the plurality of side margin layersmay be larger than a content of Si included in remaining ones of theside margin layers other than the side margin layer located on theoutermost side.

A boundary may be provided between a plurality of the layer-marginlayers adjacent to each other in the laminating direction.

A boundary may be provided between a plurality of the side margin layersadjacent to each other in the width direction.

In an electronic component according to a preferred embodiment of thepresent invention, the side margin portion in which the internalelectrode is not provided includes the plurality of side margin layers,and the outer layer portion in which the internal electrode is notprovided includes the plurality of layer-margin layers. Thus, it ispossible to reduce or prevent a difference in shrinkage behavior betweena portion as the inner layer portion in which the internal electrodesand the dielectric layers are alternately laminated and a portion as theside margin portion and the outer layer portion in which the internalelectrodes are not provided, in a firing process in manufacturing anelectronic component. It is possible to reduce or prevent an occurrenceof peeling or a gap between the layers in the laminate.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating an example of a multilayerceramic capacitor according to a preferred embodiment of the presentinvention.

FIG. 2 is a sectional view of the multilayer ceramic capacitorillustrated in FIG. 1 , taken along line II-II.

FIG. 3 is a sectional view of the multilayer ceramic capacitorillustrated in FIG. 1 , taken along line III-III.

FIGS. 4A and 4B are diagrams illustrating an example of a method ofmanufacturing the multilayer ceramic capacitor in the preferredembodiment: FIG. 4A is a schematic diagram illustrating a ceramic greensheet on which a conductive film is formed; and FIG. 4B is a schematicdiagram illustrating a form in which ceramic green sheets on which theconductive film is formed are laminated.

FIG. 5A is a diagram illustrating a state where an end portion of theconductive film in the width direction has a rippling shape; and FIG. 5Bis a sectional view illustrating a state where, regarding a firstinternal electrode formed by firing, saddle-shaped portions as thickportions of two first internal electrodes adjacent to each other in alaminating direction do not overlap each other in the laminatingdirection.

FIG. 6 is a perspective view illustration an example of an appearance ofa laminated chip produced in the middle of manufacturing the multilayerceramic capacitor.

FIG. 7A is a diagram illustrating a state where a ceramic green sheet ofa side margin portion, in which dimensions in a length direction and awidth direction are shorter than a dimension of the laminated chip, isstuck on the laminated chip; and FIG. 7B is a diagram illustrating astate where a ridge is scraped off by polishing.

FIGS. 8A and 8B are sectional views illustrating the multilayer ceramiccapacitor in which a tone adjustment layer is provided at the sidemargin portion: FIG. 8A is a diagram illustrating a case where a dummyinternal electrode as the tone adjustment layer is not connected to anexternal electrode; and FIG. 8B is a diagram illustrating a case wherethe dummy internal electrode as the tone adjustment layer is connectedto the external electrode.

FIG. 9 is a sectional view illustrating the multilayer ceramic capacitorhaving a structure in which an antioxidation layer is provided at theside margin portion.

FIG. 10 is a sectional view illustrating the multilayer ceramiccapacitor in which a first dummy internal electrode which is exposed toa first end surface of the laminate and is connected to a first externalelectrode and a second dummy internal electrode which is exposed to asecond end surface of the laminate and is connected to a second externalelectrode are provided.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, features of the present invention will be specificallydescribed with reference to preferred embodiments of the presentinvention and the accompanying drawings.

Descriptions will be made below using a multilayer ceramic capacitor asan example of an electronic component according to preferred embodimentsthe prevent invention.

The electronic component is not limited to a multilayer ceramiccapacitor as described below, and may be any other electroniccomponents, such as an inductor and an LC filter, for example.

FIG. 1 is a perspective view illustrating an example of a multilayerceramic capacitor 10 according to a preferred embodiment of the presentinvention. FIG. 2 is a sectional view of the multilayer ceramiccapacitor 10 illustrated in FIG. 1 , taken along line II-II. FIG. 3 is asectional view of the multilayer ceramic capacitor 10 illustrated inFIG. 1 , taken along line III-III.

As illustrated in FIGS. 1 to 3 , the multilayer ceramic capacitor 10preferably has a rectangular or substantially rectangular parallelepipedshape. The multilayer ceramic capacitor 10 includes a laminate 11 and apair of external electrodes 14 (14 a and 14 b). The external electrodes14 a and 14 b face each other, as illustrated in FIG. 1 .

Here, a direction in which the external electrodes 14 defining the pairface each other is a length direction L of the multilayer ceramiccapacitor 10. A direction in which internal electrodes 13 (13 a and 13b) described later are laminated is a laminating direction T. Adirection perpendicular or substantially perpendicular to both of thelength direction L and the laminating direction T is a width directionW.

If the size of the multilayer ceramic capacitor 10 is described withrespect to a dimension in the length direction L×a dimension in thewidth direction W×a dimension in the laminating direction T, sizes of,for example, about 1.6 mm×about 0.8 mm×about 0.8 mm. about 1.0 mm×about0.5 mm×about 0.5 mm, about 0.6 mm×about 0.3 mm×about 0.3 mm, about 0.4mm×about 0.2 mm×about 0.2 mm, and about 0.2 mm×about 0.1 mm×about 0.1 mmare preferable. Each of the dimensions has a tolerance of about ±10%.

The laminate 11 preferably includes a first end surface 15 a and asecond end surface 15 b opposing each other in the length direction L, afirst main surface 16 a and a second main surface 16 b opposing eachother in the laminating direction T, and a first side surface 17 a and asecond side surface 17 b opposing each other in the width direction W.

The first end surface 15 a and the second end surface 15 b extend in thewidth direction W and the laminating direction T. The first main surface16 a and the second main surface 16 b extend in the length direction Land the width direction W. The first side surface 17 a and the secondside surface 17 b extend in the length direction L and the laminatingdirection T.

The laminate 11 preferably includes rounded corners and rounded ridges.Here, the corner refers to a portion at which three sides of thelaminate 11 intersect, and the ridge refers to a portion at which twosides of the laminate 11 intersect.

As illustrated in FIGS. 2 and 3 , the laminate 11 preferably includes aninner layer portion 21, an outer layer portion 22, and a side marginportion 23.

The inner layer portion 21 includes a dielectric layer 12, a firstinternal electrode 13 a, and a second internal electrode 13 b. Thedielectric layer 12 is interposed between the first internal electrode13 a and the second internal electrode 13 b. The inner layer portion 21is configured in a manner that a plurality of first internal electrodes13 a and a plurality of second internal electrodes 13 b are alternatelylaminated with dielectric layers 12 interposed therebetween.

The dielectric layer 12 is preferably made of dielectric ceramicparticles. For example, the dielectric ceramic particle preferablycontains a perovskite type compound containing Ba and Ti as the maincomponent and has a perovskite structure. At least one of Si, Mg, andBa, for example, may preferably be added to the main components as anadditive. The dielectric layer 12 may contain rare-earth elements suchas Dy, Y, and Ho, for example. The thickness of the dielectric layer 12is preferably, for example, about 0.2 μm or more and about 10 μm orless.

Here, a particle size of the dielectric ceramic particle may be set tobe different between a central portion and an end portion of thedielectric layer 12 in the length direction L. For example, the particlesize of the dielectric ceramic particle at the central portion of thedielectric layer 12 in the length direction L is preferably larger thanthe particle size of the dielectric ceramic particle at the end portionof the dielectric layer 12 in the length direction L.

Here, a thickness of the dielectric layer 12 (interposed between thefirst internal electrode 13 a and the second internal electrode 13 b) inthe laminating direction T is referred to as an element thickness. In amultilayer ceramic capacitor 10 having an element thickness of about 0.8μm or less, a preferred relationship between an average elementthickness d of a plurality of dielectric layers 12 and the particle sizeD50 of the dielectric ceramic particle is as follows, for example:

-   -   Central portion in length direction L: 0.25d≤D50≤1.2d    -   End portion in length direction L: 0.15d≤D50≤0.50d

In order to set the particle size of the dielectric ceramic particle tobe different between the central portion and the end portion of thedielectric layer 12 of the inner layer portion 21 in the lengthdirection L, for example, a content of Mg per volume, which is includedin the dielectric layer 12 of the inner layer portion 21 is preferablyset to be different from the content of Mg per volume, which is includedin the side margin portion 23 described later. As an example, thecontent of Mg per volume, which is included in the side margin portion23 is about ten times or more as many as the content of Mg per volume,which is included in the dielectric layer 12 of the inner layer portion21. A composition of the dielectric layer 12 in the side margin portion23 is different from a composition of the dielectric layer 12 in theinner layer portion 21 in that a material having high density is used.Thus, it is possible to improve moisture resistance of the multilayerceramic capacitor 10. The difference in content of Mg may be measured bythe wavelength dispersive X-ray analysis. In a case of measuring thecontent in more detail, a transmission electron microscope is used.

The first internal electrode 13 a and the second internal electrode 13 bface each other with the dielectric layer 12 interposed therebetween inthe laminating direction T. Electrostatic capacitance is generated at aportion at which the first internal electrode 13 a and the secondinternal electrode 13 b face each other with the dielectric layer 12interposed therebetween.

The dielectric layer 12 extends in the width direction W and the lengthdirection L. The first internal electrode 13 a extends along thedielectric layer 12 in a plate shape and extends toward the first endsurface 15 a of the laminate 11. The second internal electrode 13 bextends along the dielectric layer 12 in a plate shape and extendstoward the second end surface 15 b of the laminate 11.

The first internal electrode 13 a and the second internal electrode 13 bpreferably include Ni, for example. The first internal electrode 13 aand the second internal electrode 13 b may preferably include, forexample, metal such as Cu, Ag, Pd, Ag—Pd alloys, and Au, in addition toNi. The first internal electrode 13 a and the second internal electrode13 b may preferably include the same dielectric particles as thedielectric particles of the dielectric layer 12. The thickness of eachof the first internal electrode 13 a and the second internal electrode13 b is preferably about 0.3 μm or more and about 2.0 μm or less, forexample.

A content of Si included at the end portions of the first internalelectrode 13 a and the second internal electrode 13 b in the widthdirection W is preferably more than the content of Si included at thecentral portions of the first internal electrode 13 a and the secondinternal electrode 13 b in the width direction W. The difference incontent of Si may be measured by the wavelength dispersive X-rayanalysis. In a case of measuring the content in more detail, atransmission electron microscope, for example, is preferably used.

When a section of the multilayer ceramic capacitor 10 in the widthdirection W and the laminating direction T is viewed from the lengthdirection L, positions of the end portions of the internal electrodes 13may be aligned in the laminating direction or may have a relationship inwhich the central portion in the laminating direction bulges outwardfrom the end portion in the laminating direction. In other words, thedimension of the internal electrode 13 (located at the central portionin the laminating direction) in the width direction W may be equal to orlarger than the dimension of the internal electrode 13 (located at theend portion in the laminating direction) in the width direction W.

The outer layer portion 22 is preferably provided on both outsides ofthe inner layer portion 21 in the laminating direction T. That is, theinner layer portion 21 is preferably interposed between two outer layerportions 22 provided on both the outer sides in the laminating directionT.

When any section of the laminate 11 in the laminating direction T andthe width direction W is viewed from the length direction L, the outerlayer portion 22 refers to a region in which neither the first internalelectrode 13 a nor the second internal electrode 13 b is provided,except for the side margin portion 23 described later.

The outer layer portion 22 includes a plurality of layer-margin layers.Specifically, the outer layer portion 22 includes an outer layer-marginlayer 22 a and an inner layer-margin layer 22 b. The outer layer-marginlayer 22 a is located on the first main surface 16 a and the second mainsurface 16 b sides of the laminate 11. The inner layer-margin layer 22 bis located on the inner layer portion 21 side.

A boundary between the outer layer-margin layer 22 a and the innerlayer-margin layer 22 b may be observed by a difference ofsinterability. Thus, it is possible to easily recognize that the outerlayer portion 22 includes the plurality of layer-margin layers 22 a and22 b, by using an optical microscope, for example. That is, the boundaryis provided between the outer layer-margin layer 22 a and the innerlayer-margin layer 22 b.

The dimension of the outer layer portion 22 in the laminating directionT is preferably about 5 μm or more and about 100 μm or less, forexample. In the present preferred embodiment, the dimension of the outerlayer-margin layer 22 a in the laminating direction T is larger than thedimension of the inner layer-margin layer in the laminating direction T.For example, the dimension of the outer layer-margin layer in thelaminating direction T is preferably about 5 μm or more and about 95 μmor less, and the dimension of the inner layer-margin layer in thelaminating direction T is preferably about 5 μm or more and about 95 μmor less.

The outer layer portion 22 is preferably made of a dielectric ceramicmaterial which is a dielectric and has a perovskite structure in which,for example, BaTiO₃ is provided as the main component, for example. Asan additive, Si, for example, is preferably added to the main component.

The content of Si in the outer layer-margin layer 22 a is more than thecontent of Si in the inner layer-margin layer 22 b. That is, a moleratio of Si/Ti in the outer layer-margin layer 22 a is higher than themole ratio of Si/Ti in the inner layer-margin layer 22 b. For example,the mole ratio of Si/Ti in the outer layer-margin layer 22 a ispreferably about 3.5 or more and about 6.0 or less, and the mole ratioof Si/Ti in the inner layer-margin layer is preferably about 0.02 ormore and about 3.5 or less. In a case of measuring the mole ratio ofSi/Ti, a transmission electron microscope, for example, is preferablyused.

Here, Si acts as a sintering aid. Thus, the outer layer-margin layer 22a obtained by firing in manufacturing the multilayer ceramic capacitor10 has a denser structure than the structure of the inner layer-marginlayer 22 b. Thus, it is possible to improve solidity of the outer layerportion 22. Accordingly, cracks or chips occur less frequently in theouter layer portion 22, and it is possible to reduce or preventpenetration of moisture into the inside. It is possible to achieve bothmoisture resistance/solidity of the outer layer portion 22 andhigh-temperature reliability/voltage resistance in the vicinity of theouter layer portion 22. Since the outer layer portion 22 includes theouter layer-margin layer 22 a and the inner layer-margin layer 22 b, itis possible to stop the expansion of cracks, at an interface between theouter layer-margin layer 22 a and the inner layer-margin layer 22 b evenin a case where cracks occur in the outer layer portion.

Since the outer layer portion 22 includes the plurality of layer-marginlayers 22 a and 22 b, it is possible to reduce or prevent a differencein shrinkage behavior between the inner layer portion 21 in which theinternal electrode 13 is provided, and the outer layer portion 22 inwhich the internal electrode 13 is not provided, in a firing process inmanufacturing. That is, the inner layer-margin layer 22 b has a functionto reduce or prevent the difference in shrinkage behavior between theinner layer portion 21 and the outer layer-margin layer 22 a, and thus,it is possible to reduce or prevent the difference in shrinkage behaviorbetween the inner layer portion 21 and the outer layer portion 22.

When any section of the laminate 11 in the length direction L and thewidth direction W is viewed from the laminating direction T, the sidemargin portion 23 refers to a region in which neither the first internalelectrode 13 a nor the second internal electrode 13 b is provided. Asillustrated in FIG. 3 , the side margin portion 23 is located on bothouter sides in the width direction W. That is, two side margin portions23 are provided to interpose the inner layer portion 21 and the outerlayer portion 22 in the width direction W.

The side margin portion 23 includes a plurality of side margin layerslaminated in the width direction W. Specifically, the side marginportion 23 includes an outer side margin layer 23 a and an inner sidemargin layer 23 b. The outer side margin layer 23 a is located on thefirst side surface 17 a and the second side surface 17 b sides of thelaminate 11. The inner side margin layer 23 b is located on the innerlayer portion 21 side.

A boundary between the outer side margin layer 23 a and the inner sidemargin layer 23 b may be observed by a difference of sinterability.Thus, it is possible to easily recognize that the side margin portion 23includes the plurality of side margin layers 23 a and 23 b, by using anoptical microscope. That is, the boundary is provided between the outerside margin layer 23 a and the inner side margin layer 23 b.

The dimension of the side margin portion 23 in the width direction W is,for example, about 5 μm or more and about 40 μm or less, and preferablyabout 20 μm or less. The dimension of the outer side margin layer 23 ain the width direction W is larger than the dimension of the inner sidemargin layer 23 b in the width direction W. For example, the dimensionof the outer side margin layer 23 a in the width direction W ispreferably about 5 μm or more and about 20 μm or less, and the dimensionof the inner side margin layer 23 b in the width direction W ispreferably about 0.1 μm or more and about 20 μm or less.

The dimension of the side margin portion 23 in the width direction Wmeans an average dimension calculated by a measurement result which isobtained by measuring the dimension of the side margin portion 23 at aplurality of locations in the laminating direction T.

A non-limiting example of a method of measuring the dimension of theside margin portion 23 in the width direction W is as follows.

Firstly, a surface (referred to as “a WT section” below) of themultilayer ceramic capacitor 10 in the width direction W and thelaminating direction T is exposed. Then, the end portions of the firstinternal electrode 13 a and the second internal electrode 13 b in thewidth direction W and any one of the two side margin portions 23 locatedon the outer sides in the width direction W, in the WT section, areimaged by an optical microscope to be provided in the same field ofview. Imaging locations are three locations of an upper portion, acentral portion, and a lower portion in the laminating direction T. Inthe upper portion, the central portion, and the lower portion, aplurality of line segments parallel or substantially parallel to thewidth direction W extends to the first side surface 17 a and the secondside surface 17 b from the end portions of the first internal electrode13 a and the second internal electrode 13 b in the width direction W,and then, the length of each of the line segment is measured.

Regarding the length of the line segment measured in this manner, anaverage value of the lengths at each of the upper portion, the centralportion, and the lower portion is calculated. The dimension of the sidemargin portion 23 in the width direction W is obtained by averaging theaverage values.

With a similar method, the dimension of the outer layer portion 22 inthe laminating direction T may be measured. That is, an averagedimension calculated by a measurement result which is obtained bymeasuring the dimension of the outer layer portion 22 in the laminatingdirection T at a plurality of places in the length direction L isobtained.

The side margin portion 23 is preferably made of a dielectric ceramicmaterial which is a dielectric and has a perovskite structure in which,for example, BaTiO₃ is provided as the main component. As an additive,Si, for example, is preferably added to the main component.

The content of Si in the outer side margin layer 23 a is more than thecontent of Si in the inner side margin layer 23 b. That is, a mole ratioof Si/Ti in the outer side margin layer 23 a is higher than the moleratio of Si/Ti in the inner side margin layer 23 b. For example, themole ratio of Si/Ti in the outer side margin layer 23 a is preferablyabout 3.5 or more and about 6.0 or less, and the mole ratio of Si/Ti inthe inner side margin layer is preferably about 0.02 or more and about3.5 or less. In a case of measuring the mole ratio of Si/Ti, a WDX or aTEM, for example, may be used.

As described above, since Si acts as the sintering aid, the outer sidemargin layer 23 a obtained by firing in manufacturing the multilayerceramic capacitor 10 has a denser structure than the structure of theinner side margin layer 23 b. Thus, it is possible to improve solidityof the side margin portion 23. Accordingly, cracks or chips occur lessfrequently in the side margin portion 23, and it is possible to reduceor prevent penetration of moisture into the inside. Since the sidemargin portion 23 includes the outer side margin layer 23 a and theinner side margin layer 23 b, it is possible to stop the expansion ofcracks, at an interface between the outer side margin layer 23 a and theinner side margin layer 23 b even in a case where cracks occur in theside margin portion.

Since the side margin portion 23 includes the plurality of side marginlayers 23 a and 23 b, it is possible to reduce or prevent a differencein shrinkage behavior between the inner layer portion 21 in which theinternal electrode 13 is provided, and the side margin portion 23 inwhich the internal electrode 13 is not provided, in the firing processin manufacturing. That is, the inner side margin layer 23 b has afunction to reduce or prevent the difference in shrinkage behaviorbetween the inner layer portion 21 and the outer side margin layer 23 a,and thus, it is possible to reduce or prevent the difference inshrinkage behavior between the inner layer portion 21 and the sidemargin portion 23.

A boundary is provided between the outer layer portion 22 and the sidemargin portion 23 in the laminating direction T. That is, as illustratedin FIG. 3 , the side margin portions 23 are provided on both theoutsides of the outer layer portion 22 in the width direction W. Thus,the boundary is provided between the outer layer portion 22 and the sidemargin portion 23 in the laminating direction T.

The first external electrode 14 a is provided on the entirety orsubstantially the entirety of the first end surface 15 a of the laminate11 and extends from the first end surface 15 a to the first main surface16 a, the second main surface 16 b, the first side surface 17 a, and thesecond side surface 17 b. The first external electrode 14 a iselectrically connected to the first internal electrode 13 a.

The second external electrode 14 b is provided on the entirety orsubstantially the entirety of the second end surface 15 b of thelaminate 11 and extends from the second end surface 15 b to the firstmain surface 16 a, the second main surface 16 b, the first side surface17 a, and the second side surface 17 b. The second external electrode 14b is electrically connected to the second internal electrode 13 b.

In the present preferred embodiment, as illustrated in FIG. 2 , thefirst external electrode 14 a includes a three-layer structure definedby a first base electrode layer 141 a, a first lower plating layer 142 aon the surface of the first base electrode layer 141 a, and a firstupper plating layer 143 a on the surface of the first lower platinglayer 142 a.

The first base electrode layer 141 a covers the entirety orsubstantially the entirety of the first end surface 15 a of the laminate11 and to cover a portion of each of the first side surface 17 a and thesecond side surface 17 b and a portion of each of the first main surface16 a and the second main surface 16 b from a portion at which the firstbase electrode layer 141 a covers the first end surface 15 a.

In the present preferred embodiment, as illustrated in FIG. 2 , thesecond external electrode 14 b includes a three-layer structure definedby a second base electrode layer 141 b, a second lower plating layer 142b on the surface of the second base electrode layer 141 b, and a secondupper plating layer 143 b on the surface of the second lower platinglayer 142 b.

The second base electrode layer 141 b covers the entirety orsubstantially the entirety of the second end surface 15 b of thelaminate 11 and to cover a portion of each of the first side surface 17a and the second side surface 17 b and a portion of each of the firstmain surface 16 a and the second main surface 16 b from a portion atwhich the second base electrode layer 141 b covers the second endsurface 15 b.

The first base electrode layer 141 a and the second base electrode layer141 b preferably contain, for example, metal such as Ni, Cu, Ag, Pd,Ag—Pd alloys, or Au. A plurality of first base electrode layers 141 aand a plurality of second base electrode layers 141 b may be provided.

The first base electrode layer 141 a and the second base electrode layer141 b may be formed by, for example, co-firing, that is: being firedsimultaneous with the first internal electrode 13 a and the secondinternal electrode 13 b, or may instead be formed by post-firing inwhich a conductive paste is applied onto the laminate 11, and then isbaked. In a case where the first base electrode layer 141 a and thesecond base electrode layer 141 b are formed by co-firing, for example,it is preferable that the first internal electrode 13 a and the secondinternal electrode 13 b contain Ni, and the first base electrode layer141 a and the second base electrode layer 141 b also contain Ni. Thefirst base electrode layer 141 a and the second base electrode layer 141b may be formed by direct plating or may be formed by hardening a resinlayer including conductive particles and thermosetting resin, forexample.

The first lower plating layer 142 a and the second lower plating layer142 b preferably contain Ni, for example, in order to prevent solderbreakage. The first lower plating layer 142 a and the second lowerplating layer 142 b may contain, for example, metal such as Cu, Ag, Pd,Ag—Pd alloys, or Au in addition to Ni.

The first upper plating layer 143 a and the second upper plating layer143 b preferably contain Sn, for example, in order to improve themountability. The first upper plating layer 143 a and the second upperplating layer 143 b may contain, for example, metal such as Cu, Ag, Pd,Ag—Pd alloys, or Au in addition to Sn.

The configurations of the first external electrode 14 a and the secondexternal electrode 14 b are not limited to the above-describedconfiguration. For example, the first external electrode 14 a and thesecond external electrode 14 b may be formed by plating in a manner ofperforming direct plating on the laminate 11 if so desired.

Method of Manufacturing Multilayer Ceramic Capacitor

A non-limiting example of a method of manufacturing the multilayerceramic capacitor 10 having the above-described structure will bedescribed below. FIGS. 4A and 4B are diagrams illustrating the exampleof the manufacturing the multilayer ceramic capacitor 10 in accordancewith a preferred embodiment of the present invention. FIG. 4A is aschematic diagram illustrating a ceramic green sheet in which aconductive film is formed. FIG. 4B is a schematic diagram illustrating aform in which ceramic green sheets in which the conductive film isformed are laminated.

Firstly, a perovskite type compound including Ba and Ti is preferablyprepared as a dielectric material.

At least one of Si, Mg, and Ba as an additive, and an organic binder, anorganic solvent, a plasticizer, and a dispersant, for example, aremixed, at a predetermined ratio, to dielectric powder obtained from thedielectric material, and thereby a ceramic slurry is produced.

Ceramic green sheets 50 a and 50 b are produced by coating surfaces of aplurality of resin films (not illustrated) with the produced ceramicslurry. The ceramic green sheet 50 b is alternately laminated with theceramic green sheet 50 a. The ceramic green sheets 50 a and 50 b may beproduced, for example, by using a die coater, a gravure coater, or amicrogravure coater.

Then, as illustrated in FIG. 4A, a conductive paste used in making theinternal electrode is applied onto the surfaces of the ceramic greensheets 50 a and 50 b in a stripe shape, and then is dried. Here, adirection in which the conductive paste used in making the internalelectrode extends in the stripe shape is set to an X-direction, and adirection perpendicular or substantially perpendicular to theX-direction on the ceramic green sheet is set to a Y-direction. In thismanner, a conductive film 52 a (52 b) becoming the first internalelectrode 13 a (second internal electrode 13 b) is formed. As theapplying method, various methods such as screen printing, ink jetprinting, and gravure printing, for example, can be used.

A ceramic green sheet used in making the outer layer portion, whichbecomes the outer layer portion 22, is produced. A perovskite compoundcontaining Ba and Ti is prepared as a dielectric material used inproducing the ceramic green sheet for the outer layer portion. Anadditive preferably containing at least Si, an organic binder, anorganic solvent, a plasticizer, and a dispersant are mixed, at apredetermined ratio, to dielectric powder obtained from the dielectricmaterial, and thereby a ceramic slurry is produced. The ceramic greensheet used in making the outer layer portion is produced using theproduced ceramic slurry.

Here, the content of Si included in the ceramic slurry for forming theouter layer-margin layer 22 a of the outer layer portion 22 is adjustedto be larger than the content of Si included in the ceramic slurry usedin forming the inner layer-margin layer 22 b. For example, in theceramic slurry used in making the outer layer-margin layer, the contentof Si is preferably set to be about 3.5 mol or more and about 6.0 mol orless with respect to about 1 mol of Ti. In the ceramic slurry used inmaking the inner layer-margin layer, the content of Si is preferably setto be about 0.02 mol or more and about 3.5 mol or less with respect toabout 1 mol of Ti.

The ceramic slurry is applied such that the thickness of the ceramicgreen sheet used in forming the outer layer-margin layer 22 a is thickerthan the thickness of the ceramic green sheet for forming the innerlayer-margin layer 22 b.

The ceramic green sheet becoming the inner layer-margin layer 22 b islaminated on the ceramic green sheet becoming the outer layer-marginlayer 22 a. Then, a plurality of the ceramic green sheets 50 a and 50 bin which the conductive films 52 a and 52 b are formed is laminated in astate of being shifted from each other in the Y-direction, asillustrated in FIG. 4B. In this state, a mother laminate is obtained bylaminating the ceramic green sheet becoming the inner layer-margin layer22 b and the ceramic green sheet becoming the outer layer-margin layer22 a in this order.

Here, when the conductive films 52 a and 52 b are formed in the ceramicgreen sheets 50 a and 50 b by applying the paste, the end portions ofthe conductive films 52 a and 52 b in the width direction may have arippling shape, not a straight line (see FIG. 5A). In this case, asaddle-shaped portion having a thickness thicker than others is formedat a portion of the conductive films 52 a and 52 b, which bulges in thewidth direction. If saddle-shaped portions are provided at positionsoverlapping each other in the laminating direction T, the ceramic greensheet becomes thin at this portion. Thus, in a case of obtaining themultilayer ceramic capacitor, there is a problem in that reliabilitydecreases.

Thus, when a plurality of ceramic green sheets 50 a is laminated suchthat end portions of conductive films 52 a are located at the same orsubstantially the same position in the laminating direction T, thelamination is performed after the positions in the X-direction areadjusted such that saddle-shaped portions of the conductive films 52 ain two ceramic green sheets 50 a which are closest to each other in atleast the laminating direction T do not overlap each other. Thus,regarding the first internal electrode 13 a formed by firing, asillustrated in FIG. 5B, it is possible to prevent overlapping of thesaddle-shaped portions 130 of two first internal electrodes 13 a whichare closest to each other in the laminating direction T.

Similarly, when ceramic green sheets 50 b are laminated such that endportions of conductive films 52 b are located at the same orsubstantially the same position in the laminating direction T, thelamination is performed after the positions in the X-direction areadjusted such that saddle-shaped portions of the conductive films 52 bin two ceramic green sheets 50 b which are closest to each other in atleast the laminating direction T do not overlap each other. Thus,regarding the second internal electrode 13 b formed by firing, it ispossible to prevent overlapping of the saddle-shaped portions of twosecond internal electrodes 13 b which are closest to each other in thelaminating direction T.

The mother laminate is preferably pressed by a method, such as rigidpress or isostatic press, for example. The pressed mother laminate iscut out to have a chip shape, and thus a laminated chip 60 illustratedin FIG. 6 is obtained.

As illustrated in FIG. 6 , only the conductive film 52 a of the ceramicgreen sheet 50 a is exposed to one end surface of the laminated chip 60,and only the conductive film 52 b of the ceramic green sheet 50 b isexposed to the other end surface. The conductive film 52 a of theceramic green sheet 50 a and the conductive film 52 b of the ceramicgreen sheet 50 b are exposed to each side surface of the laminated chip60.

A ceramic green sheet for the side margin portion, which becomes theside margin portion 23 is produced. A perovskite compound including Baand Ti is preferably prepared as a dielectric material for producing theceramic green sheet for the side margin portion. An additive containingat least Si, an organic binder, an organic solvent, a plasticizer, and adispersant, for example, are mixed, at a predetermined ratio, todielectric powder obtained from the dielectric material, and thereby aceramic slurry is produced. The ceramic green sheet for the side marginportion is produced using the produced ceramic slurry.

Preferably, many ceramic particles having a large particle shape indexindicating the degree of roundness, that is, ceramic particles havinguniform or substantially uniform shape and particle size are included inthe ceramic green sheet for the side margin portion, in particular, inthe ceramic green sheet use in forming the inner side margin layer 23 b.If the particle size and the shape of the ceramic particles are uniformor substantially uniform, the resin included in the ceramic green sheetis likely to ooze through the surface. Thus, adhesiveness when theceramic green sheet for the side margin portion is adhered on thelaminated chip is improved.

A portion becoming the inner layer portion 21 and a portion becoming theside margin portion 23 shrink by the subsequent firing treatment.However, in order to reduce or prevent the difference in amount ofshrinkage between the portions, the amount of the resin included in theceramic green sheet for the side margin portion is set to be larger thanthe amount of the resin included in the ceramic green sheet used informing the inner layer portion 21.

When the ceramic slurry is produced, the content of Si included in theceramic slurry used in forming the outer side margin layer 23 a isadjusted to be larger than the content of Si included in the ceramicslurry for forming the inner side margin layer 23 b. For example, in theceramic slurry of the outer layer-margin layer, the content of Si ispreferably set to be about 3.5 mol or more and about 6.0 mol or lesswith respect to about 1 mol of Ti. In the ceramic slurry used in makingthe inner layer-margin layer, the content of Si is preferably set to beabout 0.02 mol or more and about 3.5 mol or less with respect to about 1mol of Ti.

The ceramic slurry is applied such that the thickness of the ceramicgreen sheet used in forming the outer side margin layer 23 a is thickerthan the thickness of the ceramic green sheet used in forming the innerside margin layer 23 b.

Then, the ceramic green sheet used to make the inner side margin portionis laminated on the ceramic green sheet used in making the outer sidemargin portion, and bonding is performed, and thus the ceramic greensheet used in making the side margin portion, which has a two-layerstructure, is obtained.

The ceramic green sheet used in making the inner side margin portion inthe ceramic green sheet used in making the side margin portion and theside surface of the laminated chip 60, on which the conductive films 52a and 52 b are exposed are preferably caused to face each other and arepressed by punching, for example. Thus, a layer becoming the side marginportion 23 is formed. With the similar method, the layer becoming theside margin portion 23 is formed on the opposite side surface.

At this time, the ceramic green sheet used in making the side marginportion is not adhered on the ridge of the laminated chip on which thelayer becoming the side margin portion 23 is formed. That is, asillustrated in FIG. 7A, for a ceramic green sheet 70 used in making theside margin portion, a ceramic green sheet in which the dimension in thelength direction L is shorter than the dimension of the laminated chip60 in the length direction L and the dimension in the width direction Wis shorter than the dimension of the laminated chip 60 in the widthdirection W is prepared. Then, the ceramic green sheet 70 is preferablyadhered to the laminated chip 60 while aligning the center positions ofthe ceramic green sheet and the laminated chip.

Then, barrel polishing is performed on the laminated chip 60 on whichthe ceramic green sheet 70 used in making the side margin portion isstuck. Thus, the corners and ridges are rounded, but the corners areeasier to be scraped than ridges. However, since the ceramic green sheetused in making the side margin portion is not adhered on the ridge, itis possible to reduce the amount of polishing and a polishing time toform the ridge into a desired shape (see FIG. 7B). Thus, it is possibleto reduce or prevent an occurrence of a situation in which the corner isscraped too much.

In a finished state, it is preferable that the corners and ridges of theouter layer-margin layer 22 a in the outer layer portion 22 are rounded,but the inner layer-margin layer 22 b are not scrapped. It is preferablethat the corners and ridges of the outer side margin layer 23 a in theside margin portion 23 are rounded, but the inner side margin layer 23 bare not scrapped.

Then, barrel polishing is preferably performed on the laminated chip 60on which the ceramic green sheet 70 for the side margin portion isadhered. Degreasing treatment is preferably performed on the laminatedchip under a predetermined condition in an atmosphere of nitrogen. Then,firing treatment is performed at a predetermined temperature in anatmosphere of a mixture of nitrogen, hydrogen, and steam.

Thus, a sintered laminate is obtained.

Then, an external electrode paste including Cu, for example, as the maincomponent is applied on both end surfaces of the sintered laminate, andthe resultant is baked. Thus, the first base electrode layer 141 aconnected to the first internal electrode 13 a and the second baseelectrode layer 141 b connected to the second internal electrode 13 bare formed. The first lower plating layer 142 a is formed on the surfaceof the first base electrode layer 141 a by Ni plating, for example, andthe first upper plating layer 143 a is formed on the surface of thefirst lower plating layer 142 a by Sn plating, for example, and thus thefirst external electrode 14 a is formed. With the similar method, thesecond external electrode 14 b is formed.

The laminated chip and the external electrode paste may be firedsimultaneously.

The multilayer ceramic capacitor 10 is preferably produced with theabove-described method. The above-described manufacturing method is anon-limiting example, and the method of manufacturing the multilayerceramic capacitor 10 is not limited to the above-described manufacturingmethod.

Modification Example 1

In a case where the dimension of the side margin portion 23 in the widthdirection W is shorter than the dimension of the outer layer portion 22in the laminating direction T, when the multilayer ceramic capacitor 10is viewed from the outside thereof in the width direction W, theinternal electrode 13 is able to be seen through. However, when viewedfrom the outside thereof in the laminating direction T, the internalelectrode 13 are not able to be seen though and may be seen with adifferent color tone.

Therefore, as illustrated in FIG. 8 , a tone adjustment layer 80 may bedisposed at a position having the same or substantially the same depthas the dimension of the side margin portion 23 in the width direction W,from each of the first main surface 16 a and the second main surface 16b of the multilayer ceramic capacitor 10, which correspond to the outerlayer portion 22.

That is, the dimension of the side margin portion 23 in the widthdirection W is equal or substantially equal to a distance from each ofthe first main surface 16 a and the second main surface 16 b to the toneadjustment layer 80.

The tone adjustment layer 80 is a layer that causes a color tone whenthe multilayer ceramic capacitor 10 is viewed from the outside thereofin the laminating direction T to be identical or substantially identicalto a color tone when viewed from the outside thereof in the widthdirection W. For example, a dummy internal electrode made of the samematerial as the internal electrode 13 may preferably be disposed as thetone adjustment layer 80.

The dummy internal electrode may not be electrically connected to theexternal electrode 14 as illustrated in FIG. 8A, or may be electricallyconnected to the external electrode 14 as illustrated in FIG. 8B. In acase where the dummy internal electrode electrically connected to theexternal electrode 14 is provided, the dummy internal electrode is setto be electrically connected to the external electrode 14 electricallyconnected to the internal electrode 13 at the closest position in thelaminating direction T.

Since the tone adjustment layer 80 is provided, it is possible to reducea difference between a color tone when the multilayer ceramic capacitor10 is viewed from the outside thereof in the width direction W and acolor tone when viewed from the outside thereof in the laminatingdirection T.

Modification Example 2

The end portion of the internal electrode 13 in the width direction W isprovided at a position close to the surface during firing, and thusoxidation easily proceeds. Therefore, an antioxidation layer maypreferably be disposed in the side margin portion 23.

FIG. 9 is a sectional view illustrating the multilayer ceramic capacitor10 having a structure in which an antioxidation layer 90 is preferablyprovided in the side margin portion 23. In the example illustrated inFIG. 9 , the antioxidation layer 90 is provided between the outer sidemargin layer 23 a and the inner side margin layer 23 b of the sidemargin portion 23. However, a position at which the antioxidation layer90 is provided is not limited to the position between the outer sidemargin layer 23 a and the inner side margin layer 23 b.

The antioxidation layer 90 is preferably, for example, a dummy internalelectrode made of the same material as the internal electrode 13. In acase where the dummy internal electrode is disposed, the dummy internalelectrode is not electrically connected to the external electrode 14.However, the dummy internal electrode may be electrically connected tothe external electrode 14.

Since the antioxidation layer 90 is provided in the side margin portion23, it is possible to prevent oxidation of the end portion of theinternal electrode 13 in the width direction W during firing. Since thedummy internal electrode is disposed, as the antioxidation layer 90, inthe side margin portion 23, it is possible to reduce a differencebetween the amount of shrinkage of the side margin portion 23 and theamount of shrinkage of the inner layer portion 21 during firing.

Modification Example 3

As illustrated in FIG. 10 , a first dummy internal electrode 101 whichis exposed to the first end surface 15 a and is connected to the firstexternal electrode 14 a and a second dummy internal electrode 102 whichis exposed to the second end surface 15 b and is connected to the secondexternal electrode 14 b may be provided.

The first dummy internal electrode 101 is preferably provided at thesame or substantially the same position as the second internal electrode13 b in the laminating direction T and is provided on the first endsurface 15 a side on which the second internal electrode 13 b is notextended. Thus, the first dummy internal electrode 101 is notelectrically connected to the second internal electrode 13 b. Since thefirst dummy internal electrode 101 connected to the first externalelectrode 14 a is provided at a position at which the second internalelectrode 13 b is not extended, a difference of the thickness between aposition at which the second internal electrode 13 b is provided and aposition at which the second internal electrode 13 b is not provided isreduced. The first dummy internal electrode 101 is a portion of theinternal electrode of a neighboring laminated chip 60 duringmanufacturing. Thus, it is possible to reduce or prevent peeling of thedielectric layer 12 when the laminate is cut out in a chip shape.

The second dummy internal electrode 102 is preferably provided at thesame or substantially the same position as the first internal electrode13 a in the laminating direction T and is provided on the second endsurface 15 b side on which the first internal electrode 13 a is notextended. Thus, the second dummy internal electrode 102 is notelectrically connected to the first internal electrode 13 a. Since thesecond dummy internal electrode 102 connected to the second externalelectrode 14 b is provided at a position at which the first internalelectrode 13 a is not extended, a difference of the thickness between aposition at which the first internal electrode 13 a is provided and aposition at which the first internal electrode 13 a is not provided isreduced. The second dummy internal electrode 102 is a portion of theinternal electrode of a neighboring laminated chip 60 in manufacturing.Thus, it is possible to reduce or prevent peeling of the dielectriclayer 12 when the laminate is cut out in a chip shape.

The present invention is not limited to the above-described preferredembodiments and the modification examples, and various applications andmodifications may be made within the scope of the present invention.

The descriptions are made on the assumption that the outer layer portion22 preferably includes the two layers of the outer layer-margin layer 22a and the inner layer-margin layer 22 b. However, the outer layerportion 22 may include three layers or more, for example. In this case,the content of Si included in the layer-margin layer located on theoutermost side in the laminating direction T among the plurality oflayer-margin layers is set to be larger than the content of Si includedin the layer-margin layers other than the layer-margin layer located onthe outermost side.

The descriptions are made on the assumption that the side margin portion23 preferably includes the two layers of the outer side margin layer 23a and the inner side margin layer 23 b. However, the side margin portion23 may include three layers or more, for example. In this case, thecontent of Si included in the side margin layer located on the outermostside in the width direction W among the plurality of side margin layersis set to be larger than the content of Si included in the side marginlayers other than the side margin layer located on the outermost side.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. An electronic component comprising: a laminateincluding a plurality of dielectric layers and a plurality of internalelectrodes that are alternately laminated; and an external electrodeelectrically connected to the plurality of internal electrodes; whereinthe plurality of dielectric layers include dielectric ceramic particles,a particle size of the dielectric ceramic particles in a central portionof the dielectric layers is different from a particle size of thedielectric ceramic particles in an end portion of the dielectric layersin the length direction; the laminate includes: a first main surface anda second main surface opposing each other in a laminating direction; afirst side surface and a second side surface opposing each other in awidth direction perpendicular or substantially perpendicular to thelaminating direction; and a first end surface and a second end surfaceopposing each other in a length direction perpendicular or substantiallyperpendicular to the laminating direction and the width direction; aside margin portion is provided in a region in which the plurality ofinternal electrodes are not provided when a cross section of thelaminate having the length direction and the width direction is viewedfrom the laminating direction; an outer layer portion includes aplurality of layer-margin layers laminated in the laminating direction,the outer layer portion being a region in which the plurality ofinternal electrodes is not provided, in addition to the side marginportion, when a cross section of the laminate having the laminatingdirection and the width direction is viewed from the length direction;and a dimension of the outer layer portion in the laminating directionis about 5 μm or more and about 95 μm or less.
 2. The electroniccomponent according to claim 1, wherein a boundary is provided betweenthe side margin portion and the outer layer portion in the laminatingdirection.
 3. The electronic component according to claim 1, wherein Siis included in the plurality of layer-margin layers; and a content of Siincluded in at least one of the layer-margin layers located on anoutermost side in the laminating direction among the plurality oflayer-margin layers is larger than a content of Si included in remainingones of the layer-margin layers other than the one of the layer-marginlayers located on the outermost side.
 4. The electronic componentaccording to claim 1, wherein a boundary is provided between a pluralityof the layer-margin layers adjacent to each other in the laminatingdirection.
 5. The electronic component according to claim 4, wherein theboundary is defined by a difference in sinterability between materialdefining the plurality of the layer-margin layers adjacent to each otherin the laminating direction.
 6. The electronic component according toclaim 1, wherein a total thickness of an outer one of the plurality ofthe layer-margin layers adjacent in the laminating direction is greaterthan a total thickness of an inner one of the plurality of thelayer-margin layers adjacent in the laminating direction.
 7. Theelectronic component according to claim 1, wherein the externalelectrode includes a three-layer structure defined by a base electrodelayer, a lower plating layer on a surface of the first base electrodelayer, and an upper plating layer on a surface of the first lowerplating layer.
 8. The electronic component according to claim 7, whereinthe base electrode layer includes Ni, Cu, Ag, Pd, Ag—Pd alloys, or Au;the plurality of internal electrodes include Ni; the lower layer platinglayer includes Ni; and the external electrode layer includes Sn.
 9. Theelectronic component according to claim 1, wherein corners and ridges ofan outer one of the plurality of the layer-margin layers are rounded,and corners and ridges of an inner one of the plurality of thelayer-margin layers are not rounded.
 10. The electronic componentaccording to claim 1, wherein a color tone adjustment layer is providedwithin the outer layer portion.
 11. The electronic component accordingto claim 10, wherein the color tone adjustment layer is defined by adummy internal electrode that is not electrically connected to theexternal electrode.
 12. The electronic component according to claim 10,wherein the color tone adjustment layer is defined by a dummy internalelectrode that is electrically connected to the external electrode. 13.The electronic component according to claim 1, wherein an antioxidationlayer is provided within the side margin portion, the antioxidationlayer being defined by a dummy internal electrode which is notelectrically connected to the external electrode.
 14. The electroniccomponent according to claim 1, wherein the laminate further includes afirst dummy internal electrode that is exposed to the first end surfaceand a second dummy internal electrode that is exposed to the second endsurface.